Heart diseases are increasingly common in adults of all ages. Recent statistics have stated that sixty million North Americans suffer from heart disease. Because the North American society is getting older, the risk of suffering from heart diseases increases every year. People are now more aware of their health and need ways to apply preventive medicine.
An electrocardiogram (ECG/EKG) is an electrical recording of the heart that is used in the investigation of heart disease. Cardiologists have confirmed the urgent need for devices that can be worn for a long period to provide an ECG covering more than twenty-four hours. The idea is to enable the observation of cardiac events that are not regularly present in heart activity.
Cardiac contractions are the result of a well orchestrated electrical phenomenon called depolarization. Cell membranes move from their negative resting potential to a more positive threshold which ultimately stimulates them to contract. In the myocardium there are specialized fibers that are very conductive and allow the rapid transmission of electrical impulses across the muscle, telling them to contract. In order to maximize the force of the contraction there is uniformity in the sequence. That is, the atria contract, then the ventricles contract. This allows both sets to fill properly before ejecting the blood to its next destination. These two sections are independent, yet linked to a single impulse, (in a healthy heart,) initiated by the sinoatrial, (or sinus) node. The tissue around the valves helps to channel the impulse from the sinus node through another collection of specialized tissue, the atrioventricular node, that is situated between the two sets of chambers. This area allows slightly slower transmission of the impulse to the ventricles, allowing the atria to empty into the ventricles before they contract and force the blood to the lungs or body. This area, the A/V Node, slows the impulse down to about one twenty-fifth of the original signal then passes it through to the atrioventricular bundle, or the bundle of His. This bundle divides itself into two distinct tracts through the ventricles, the bundle branches, and on to the Purkinje fibers, where the muscle of the ventricle is stimulated to contract from the bottom up, maximizing the force of ejection.
An electrical current in the direction towards the positive end of a bipolar electrode causes a positive deflection of the stylus of the ECG. If the number of myocardial cells (dipoles) in this direction increases, the current will increase as well. The greater the current, the more positive the voltage. An electrical current in the direction away from the positive end of a bipolar electrode causes a negative deflection of the stylus of the ECG. If the number of myocardial cells (dipoles) in this direction increases, the current will increase as well. The greater the current, the more negative the voltage.
The ECG Library authored by Dean Jenkins and Stephen Gerred and found on the Internet at http://www.ecglibrary.com/ in September 2002 is a very good source of information on ECGs.
An article of particular interest with respect to artificial intelligence in medical devices was published by Ralph Begley et al. in March 2000 in the Medical Device & Diagnostic Industry Magazine at page 150 and is entitled “Adding Intelligence to Medical Devices”. This article can be found on the Internet in September 2002 at the Medical Devicelink Site at hftp://www.devicelink.com/mddi/archive/00/03/014.html.
Most portable ECGs currently available on watches or the like can only record heartbeat. Although this is sufficient to determine if a patient is under cardiac arrest, it is insufficient to detect other cardiac anomalies, defects and diseases.
Prior art portable monitor systems are manufactured by a few companies, such as the Biolog™ portable ECG by Lyppard, the CCW-CAS Cardio Perfect CE™ resting ECG system by Cardio Control, the PocketView™ 12 Lead portable ECG system by Numed, the Portable ECG/Respiration Monitor by Harvard Apparatus and the Digital Angel™ Safety and Location Monitor, ThermAlert™ Watch and Alerts by Digital Angel Corporation. These monitoring devices allow partial collection of the patient's ECG data but do not offer full collection and analysis of the data, detection of anomalies and transmission of alarms and integration with traditional medical equipment and emergency central stations. Because of these drawbacks, they cannot be used to replace traditional Holter readings and cannot ensure the patient's safety.